Ibeotois



April 6 1926,

. 1,579,794 H. K. SANDELL PIANO PLAYING DEVICE DAMPER CONTROL originalFiled June 14, 1922 4 Sheets-Sheet 1 April 6 1926.

H. K. SANDELL PIANO PLAYING DEVICE DAMPER CONTROL 4 Sbeets-$heet 2 o iFiled June 14, 1922 22 41 d andzzz,

April 6,1926.

H. K. SANDELL PIANO PLAYING DEVICE DAMPER CONTROL Original Filed June14, 1922 4 Sheets-Sheet 5 H. K. SANDELL PIANO PLAYING DEVICE DAMPERCONTROL original Filed June 14,

April 6 1926.

mm mm R an a- Nw mwfi Q I mN mm. n a. in.- v mg I] mm @b Mm wfi WJQN .mw/N% A SQ .35 3 .85 km m Patented Apr. 6, 1926.

srsrgs HENRY K. SAKDELL, o1" orrroeso; L -mom, essrsnonv 'ro trrLpsnovnnnyeogvr,

PANY, on CHICAGO,--ILLI;NOS, A oonroaserion or rumors.

rIAno-r AYIne-pnxnon DA- ann con -neon.

r s nelrapr set en.. lnd June tlw i; mel eszzn im-dad and th pp1ieati.file ,,April:.9,

e ia To all whom it may concern}- Beit 1 known that; I, HEN Y K acitizen ot-the United. States, resilclin .at Ghicagq-inthe county ofCook, and Ste of llilinois ha veinvented: a new and useful! L proyementin Piano@layingJDevice Damp;- e1 I Cont-1101s,. of which the "following;a specification,

The; present invention relates to improve: mentsnin piano. playingdevices, n nd rnore pnrticu-larly to; devices operated by; electria calfmeans controlled, by perforated; not-e shnets, or controlled 1y mennallyoperated eys as s red;

The, present; application constitutes 2r di-, vision;of my'pendingapplication No. 568; filed; June. 1% 1922-, the presentargplicn tion;pertaining; particularly to the; dninper control in.;a;p-ianoplzryingdeyice The. invention is illusti 'a ted, in, the; accom-pnnyingdrawings, in, connection with a pianopla-ying device offwhich it forinsnpart, and will be understood by reference. to the accolnpanyiljig;drawings, in whioh Eign-relie on eleyation of a, piano-play: inn;device. embodying the present invention,

the; central: portion thereof being; broken away; 2; is an end:elevation of the piano}.plagying ection illustrated in Fig. 1, shoavingin. detail; the operation of a. note- .g. inag;netand'fof the control;rnngnets 1 .2 I fort cla rn,pers;- F g3; rhows ln detail sectionzplrviewthrough the control magnets, fiir the control of; the. l hnnnier railFrgt,

shows in plan-the control magnets of Fig. 3,; 'F g. 51s 2r, sect onalVlQW through the.

action. onthe, lin,e 5 5 of Fig. 1, showing iirdeta il noteqoleyingaction: arid; the com trol r; magnets for the: operation of thehaminter-rail}; jlfilig. 6 fish sectional view through a noterpl-a-yingnmgnetgend 7 is a diagrammatic. 'view showing-the, cirenits for thecontrol ofithevarrous ports of the piano action both fromaperforatednote-sheet and from manually, operated keg- 7s and pedals.

Referring-more particularly to the drawings, the numeral 10indient-esthe' string plate of'gr piano, which may be, for example,ot'the character described andshown in my prior Patent No. 1,028,496granted June 4,

1912.; The-strings are indioatedby numeral. 11}. 'Eheectionsfor theindividnalkeys are designedqloy. nnrneral' l2 and, as'they, dovnot form.a. part, offthe'; present nwention, are

steel-{by an alter mting. current note pleying lfi t fi 51 the fi fu fiO rl r t lrwi l be, neither hereinafter described.

The length ogf stroke of the halnrnersis controllyerh by; the position,of, the .lllQIfiflbilg nm wr-l'sil 6' ar cl y arms tm unted -pin s. 6.?h ch r UPPQfiQd n he bracket-16 A. spring 16 tends to draw the,hammer-rail towards; the str ngs. At onoendaof the,hammer-rail 1 6 n pinl'i pro i s -Pill si e i r bhi. wredrnitha1 lt: roller; The pi ng e neend of the hanngnerunihoperatinglevenlfS; the. .otherend; of, which isengaged; by; the felt-coyered :hee d 19 of rod 2Q, operated; by h we s of: c ntrol mssne h y the opere-tionof the controlnnagnetQl,the rod 20 isoperated either to force-the;h'un et-mi 6.! wkto; i iw rrtlwrmost P @10n. sir ull; t e e the hamme s 2,: Q1

is RGQLHYlit-t-GQ EQ assngnenn. intormediate.po-

sition, corresnondin gly reducing the stroke, 0t the.lnrnnners.v

sewed m ne eper te hsfi he magnet 21-, andtheg rod; 2); .-to hold the,.rod

tS e en ed: n s on lxe'm de Qn ation-e o f this, cooperating magnet;will be; clearr from Figures, 3 ,zmd:I 5, Figure 3 shoW- she. a sntsnmli h r -i r 'wne. P r in, detail;

Magt 2L S;;f ID16 l' spoiler po l- 2 fi' itably, n ul te w r i nfihe. tewhich is the, mo hlerore 2 5, The, coil 2 L is formed on; cylinder ofsuitable non: magnetic 11 1flt6I-l2l 26.. At one en gl; oii'thej coils iyl-i dr ssl me r i ele s nto; the;openingthronglr; thetc oil, the innerpo tion. 0t this .n1e1nherbeing formedto, pro-.

videla, sent forthe; end of the core. 25, which su tably be providedwith a,v felt: b11511 111g. 28. to dea denthe; sound}. of; in lnaet. A

lznninated' iron; frarnsQQ of generally rec; V

tengnla-nfo r-in, c.01np le tely surrgoun th e, n a not, nndne heatingthereofi ben g. by 1tsln m nz rted COIlSf-IfLlQlHOIl 'lle rod 20;

is. SGQL-lredz. to the endo f the, core 2.5,.nnd-g passesthroughnsnitzthlehore in the member- 97 en n: he an o hs rs e 29w elt d shin inm nded-1 o mine si noise. At the, end of there-d QQ-thehen-d '19; sms-lst n, einelrmvi erl;n end t the;

m en rented;

felt pad 31, which engages the hammer-rail operating lever 18. Back ofthe head 19 is mounted a felt washer 32 on the rod 20, the purpose ofwhich will be clear from a consideration of the operation of the cooperating control magnet 23.

Magnet 23 is mounted Within an iron frame 33 which is mounted to asuitable depending supporting member 34 secured to the frame 29 of themagnet 24. Within the magnet 23 is mounted a cylinder 35 of suit ablenon-magnetic material, for example, brass. A core or armature 36 ismovably mounted within the cylinder 35. At its lower end the core 36 isprovided with a 'projecting rod portion 37 which passes through a feltbushing 38 in a suitable bore provided in the cap 39 closing the lowerend of the cylinder 35. A coil spring 40 in the lower end of thecylinder surroundsthe rod like projection 37 and bears against the endof the core 36, tending to force it upwardly. At its upper end the core36 isprovided with another rod-like projection 41, which passes througha felt bushing 42 in the cylinder 35 and also through a felt bushing 43in the cap 44 closing the upper end of the cylinder 35. At its upper endthe projection 41 is provided with a felt head 45, which normally bearsagainst the felt head 32 mounted upon the rod 20 operated by magnet 21.

The co-operation of the two magnets will be readily apparent from aconsideration of Figure 5. When the electromagnet 21 is momentarilyenergized by alternating current, the solenoid core 25 is forciblybrought to the center of the magnet and the rod 20 is actuated to pushthe end of the hammerrail operating lever 18. By this movement the feltpad 27 is brought to such a position as to entirely clear the felt head45 on the rod 41 operated by electromagnet 23, and the spring 40 in thelatter magnet, acting on the end of the core 36, forces the rod 41 andthe felt head 45 upwards against the rod 20 between the pad 32 and theframe 29. The elements are then in the position shown in Figure5. Upontie-energizing the-mag net 21, the head then serves as a stop preventingthe return of the head 19 of the rod 20, and thereby prevent the returnof the hammer-rail operating lever 18 to its normal position A momentaryclosure of the circuit energizing the magnet 21 conse quently results inplacing and holding the rod 20 in energized position, its position beingmaintained even after the n'iagnet 21 has been de-energized. lVith theparts in this position, energizing the magnet 23 causes a retraction ofthe core 36 to the center of the magnet. This draws the head 45 back toa position such as to clear the pad 32 on rod 20 and permit the latterto return toits normal position with the magnet 21 de-enerin rows, eachrow of 11 gized. By means of this arrangement, for example, if themagnets are operated from a perforated music sheet, a single perforationwill permit closure of the circuit energizing the magnet 21 and theparts operated by the magnet will be held in the position after themagnet is de-energized until a perforation permitting closure of thecircuit through magnet 23 energizes the latter. The hammer-rail lever 18is then permitted to return to its normal position under the action ofits opening 16 Dampers 46 are lifted from the spring to produce thepedaling effect by the lever 47, which is operated by a pair ofco-operating magnets 21 and 23 of substantially the same typeofconstruction as electromagnets 21 and 23, and co-operating insubstantially the samemanner. In these electromagnets, as shown inFigure 2, the various elements are indicated by the same numeralsthatindicate.corresponding elements in the electromagnets 21 and 23 inFigures 3 and 5, the sufliX a being added to the several numerals. Itwill be apparent that a momentary energizing of the magnet 21 willoperate the lever 47 to lift the dampers 46, and the latter will beretained in the lifted posi tion by cooperation of the magnet 23 untilthe latter is momentarily energized.

The cores of magnets 21 and 21 are preferably of laminated construction,as shown in Figure 4, undue heating thereof being prevented by thislaminated construction.

The construction of the individual noteplaying magnets 15 Wlll be clearfrom a co-nslderatlon of Figure 6; Each of these magnets is formed of aspool 43 of suitable insulated wire mounted in a metallic, preferablyiron frame 49. Wlthin the spool is a tube or hollow cylinder 50 ofnon-mag netic material, preferably brass. Slidably mounted within thistube is the magnetic core member 51, provided'at its ends with rod-likeprojections 52 and 53. The rodlike projection 53 passes through abushing 54 in the cap 55 inthe lower end of the tube 50 and serves as aguide for the movement of the core. The rod-like projection 52 passesthrough a similar bushing 56 in the cap 57 in the upper end of the tube50. The rodlike projection 52 is provided at its upper end with a head13 and acts as a riser for operating the piano action, shown in Figures2 and 5.

As will. be seen from Figures 1. and 5, the note-playing magnets arearranged gnets being mounted .pon an angle bar 50 en ending transverselyacross and parallel to the string frame. The angle bars 50" areinsulatably mounted upon the supporting braces 51, the insulation be ingindicated at 52 A channel bar 3 is insulatably suspended from each angle1 50 and is lined with insulating mat namesasuch as fiber, indicatedatu542%. A panel otti insulatingmateriaL-serves as-a-icover for thischannel ba-r, whichcis-iusedasRa: conduit for the electriccahles-ccontro-ll-ing thefvindividual notes. Terminals 56? are providedonnthepanels ,.to wliichiare connected one out thetQlHllDtlldGilClS-IELQ111-6E1Ql1-:O'tl1G note-playing8lGCtI'.OH;ltlgl1GtS'-,l the control lines- -'lor the corresponding;notes being-com nectcd to the corresponding terininalspinfi side thechannel box or; conduit-53$. The opposite terminals of thenoteqql-aying, electromagnetsnaredirectly connected; Withthe angle bars50 which serve as a com-mo-n connecting line for: all theelectromagnete.

The operation of the: various circuits con-i trolling themechanicaldevices= oi? the a piano will he clearfroma consideration ofFigure Inthis figure the various partsareshown dia g-raimnatically, theparts and elec-' troni-a-gnets corresponding-to those heroin hetoredescribed being-i ndica'tedi by; the same reference numerals.Taro-main connections 60 and (51 are. provided forithesupply, o t

alternating ,cunrent for the operation- 0 t thein str -ment..Thelinetidisdircctly connected Withethe contact rollec 61-, overWhichmores the i ertora-ted note sheet 6E3.Goopcratinguwith-ithecontact-roller 6 1 and thenot e-vsheet Glane aplunality' ofcontact mem hers 63 controlling the note magnets- 15-,(Ether contacts control-linothe expression devices and i the volume atsou-nth are. provid'ed as} will be hereinafter clesc'rib ed.-. From eachContact connector- Sitv leads to apoint of connection, 561 with whiclnisconnected a: terminal. linetronr the. correspond in note-playing. magnet15; The.

other tern'rinals otthe note-playing magnets.

are all. connected to a common connector or line 59 corresponding to'the. angle bar- 50 previously described. The line 50 is ccmnc'cted' with:acoil 66wWl1lCl1',=\lD I turn; is connec ed through line (37 with theother current supple," line 61; The switcln St is opened. in playin whyinc-unset: a perforatedroller. It \vill th uswhe apparent that when aperforation inasl' ee-t- 3 corresponding to given-note passeshetwceniacont-act. (SP-landcontactroll= (it, current- Will pass th-rnm'h. that contact to the corresponding.note pl L. ing magnet 15; theconnector 50 ,.the inductance ht and-the l-i-net? to the outlet lin 61;The tieredinductance oil the coil-6G Will-l determine the torcewith-Which the core the note-playing map-net centered and consequentlyWilh deter lne the volume or" sound of thenote For varying the loudnessof* tone addi-- tional means closed by circuits through the contactroller- G'l are: provided. For decreasing the current and forcorrespondingly decreasing the volume of sound, a contact 68 isprovided, which, when it engages the contact roller 61, closes a shuntcircuit lar, m anner il roi-rr contithrough the line 69 andathe coil-70to-ithe lin'cIGZ The coil lO is Woundin the same directionnas the coilGli-iand, closure of this circuit consequently increases the inductanceand dccreas s thecurrent 1 through the, notepla electromagnets J throughWhichcincuirts are closedfrom the circuit? through:- contact 68., Forprod-ucinga greater volume; otsormd, a contactTLis provided, which, whenit engagescontact rollG-l through m pertoratieinin the. notesheet.providedior the pm;pose,.vcloscs ashuntcircuit'thnough the line72. and-ith'e coil '78 to the line 67.- The coil Z3 isn'ound in areverse direction to the 'coil i 66 and. consequently rv'henu cultrentiis passedthrourgh coil 73,.the inductance s-decreased and thecurrent actuating the elcctromagnets 15 encrgizedg'While the, currentthrough contact '1 is closed, isgreater than the normal current.

ilheelectromgnets 21 and 23 controlling the hammcreailare energized by:the opera tion ofcontacts 74 and 7,5: respectively Then-i contact Telengages the contactroll 6i through a suitable perforation in, the notesheet, aci rcuitis closed through theline T6 to the elcctromagnct 21:and. line .77; lead ing to the-line 7B connecting.With-the main (S1; Asin "I16 penitorationinitho noteshcet, can si n a, in .-n'1enta-renergizing of; the elecctiffil is sui crcnt,,aswhasheen pro explained,since by cooperation of, the. core ot elcctromagnet 23,ithe core of;magnet 21' is held, in position until magnet energized. lVhe-ncontact75-enga" '1 Contact: rollL 61 thron -h aperforation 1 the noteisheehiaClKFQlllllolS closed throng, line 79 and;elec romagnet23-,cwhiclr iseneigi-z'ed to retract its-core: and; release'the core of its electromagnct21 in thoflnaamer pres, r;ious iy-v described. The (lamps controlmagnets 21" and, are controlled. in isimie 80 and-SI, respectively, Theline leading from contact 80 to elcc ict 2L is indicated bynumeral Shanaonrcontact 81 to ted hynuancra-l' 82.,

In, Figure '4' circuit are die-grammatical1y shown for the control otthe piano; playing devices from hens and pedals such as are in use inordinar ;v pianos; Then i-t is desired touse-the manual and footoperateu con.-

of the note-playing'heys, the switch closed, thereby cstahl-ishii aconnectionbetween; the line 5i)? and the line 67 shunting out theinductance 66.. The note operating 1 s are indicated die-grain maticallyin end elevation 85. The, base oteachkey. is connected by alineSti-Witll the terminal 56 01'? the correspmidi-ng; noteplay-ing, magnet15; Below. each hey are. mounted two coil springs, a longer spring 87and a shorter spring 88. The springs 87 and 88 serve as contactmemhers,the spring 87 being engaged by the'base of the key on a slightdepression of the latter and the spring 88 being engaged 011 a moreforcible depression of the key. Each of the contact springs 87 isdirectly connected with a common connector 90 leading'to a coil orinductance I 66 which is in turn connected through line 91 with thecontact roller 61 The inductance 66 p ays the same role in modulatingthe sound produced by the electromagnets being energized as does theinductance 66 in operating with the note sheet.

Forcible depression of the key causes engagement of the base of the keywith the contact spring 88 as well as the contact spring 87. Thecontacts 88 are each connected with the common connector 92, whichconnects directly with the line 91 and shunts out of the circuit theinductance 66. When a circuit through one of the contacts 88 and thebase of the key is closed, it is thus apparent that the inductance 66"is shunted around with a corresponding increase in current through theelectromagnet 15 being energized and a resulting increased volume ofsound.

To soften the tone during manual operation, the pedal 93 may beemployed. This pedal is connected to the main conductor 61 by aconnection 9 1 hen the pedal is depressed, it engages a contact 95,closing a circuit through the line 96 and coil 70 to the line 91. Thecoil 70 being wound in the same direction as the coil 66, increases theinductance in the latter and thereby decreases the current passing tothe note-playing electromagnet 15 being energized at the moment. Theoperation of the pedal 93 and the coil 70 thus corresponds to that ofthe contact 68 and the coil 70 in operation with the note sheet.

The pedal 97 controls the energizing of the damper operatin magnets 21and 23*. Vfith the switch 98 closed, the pedal is connected to the mainline 61. Normally the end of the pedal 97 engages contact 99, therebyclosing the circuit through the line 100, line 83 and electromagnets 23.On depressing pedal 97 circuit through the contact 99 is opened andcircuit through the contact 101 is closed. through the connecting line1052 and line 82 to electron'lagnet 21, energizing the lat ter to raisethe dampers is from the strings. Release of the pedal .97 breaks thecircuit through contact 191 and immediately makes the circuit throughcontact 99, thereby immediately energizing the electro-n'iagnet 23 andreleasing the damper.

The foregoing detailed, description has been given for clearness ofunderstanding only, and nounnecessary limitations should Current thenpassesbe understood therefrom, but the appended claims should beconstrued as broadly as permissible in view of the prior art.

What I regard as new, and desire to secure by Letters Patent, is:

1. In a piano action, in. combination, damper operating meansindependent of the hammer actuating means and comprising an operatingmember normally tending to move in one direction, an electromagnet coil,a movable core therein, a rod secured to said core and projectingtherefrom, its end resting against the operating member, said core beingnormally held out of central position in the magnet coil, means forpassing alternating current through the electromagnet coil to therebybring the core to the center thereof to actuate said operating memberand change the position of the hammer-rail, a second electromagnet coil,a movable core therein, means for moving said core out of position insaid second electromagnet coil, means actuated by said core for engagingand latching the core of the first-mentioned electromagnet coil when thelatter has been moved to central position, and independentlycontrollable means for passing alternating current through the secondelectromagnet coil to bring its core to its center, thereby releasingthe core of the first-mentioned electromagnet.

2. In a piano action, damper operating means normally tending to movethe damper against the strings, an electromagnet having an armatureoperated upon the closing of the electric circuit or" said magnet toactuate said operating means and retract the damper, a secondelectromagnet having a spring projected armature adapted to lock thefirst armature in projected position, said second-mentioned magnetoperating upon closure of its electric'circuit to retract its armatureand release the first-mentioned armature.

3. In a piano action, damper operating means independent of the hammeractuating means and normally tending to move the damper to thestring-engaging position, an electromagnet coil, a movable core thereinequipped with a projection having a head adapted to engage the damperoperating means, said core being normally held out of position in themagnet coil, means for energizing and de-energizing said magnet coil, asecond electron'iagnet coil, a movable core therein equipped with aprojection adapted to interlock with. said head, and means forenergizing and de-energizing said secondmentioned electromagnet coil.

HENRY K. SANDELL.

